. >>> back out to sam, walk me through the science here, how long could they be on alert in hawaii? >> dan, first of all, as soon as that earthquake happened, knowing that it's 7.7, they did all of the right things. they put the warnings out, thinking that may this would be a bad run of waves. evacuating those lower levels of hawaii were a very good idea. so, you e initially think that first wave would run away from that, remember, this is a subsiding zone, one plate is underneath another plate. a little wave or two and one or two, three, in this case four waves went out and went toward hawaii and down the coast of california as well. now, normally, you would look for the bigger waves and the bigger tsunami problems, at an 58 or 9, they did the absolute right thing by getting those sirens out. these waves have been traveling, like two to four feet in many locations, you can't give everyone the all-clear until the entire system said that the water has traveled. until the buoys have said it's all calm you can't give the all clear. there may be more aftershocks and more waves. dan? >>